Warm-up Pick up your graded Intermolecular Forces POGIL and Practice sheet. Check your answers to the Practice. a) between hexane and decane (bp=98°C) b) lower than 1-propanol (bp=78°C) c) between 2-hexane and 2-decane (bp=173°C) The cis compound has the higher bp because it has dipole-dipole forces a) He < CH4 < CH3F < NH3 b) Ne < CH3Br < CH3CN < CH3OH c) CH4 <SiH4 <GeH4 < SnH4 (all nonpolar, increased MW increases dispersion forces) O-H bond is a covalent bond where electrons are shared. Hydrogen bond I an attraction. CH3OH can hydrogen bond, which is the strongest IMF

Extra Credit: Should draw a structure with two OH groups that would allow for two hydrogen bonds, a) CH3CH2CH2NH2 (it can hydrogen bond!) b) NaCl (ionic compound) c) CaO (ionic compound; 2+/2-) CH3C=OCH3 (second answer choice) C-strongest covalent bond because F has the smallest atomic radius due to a large Zeff

Warm-up Rank the types of intermolecular forces in terms of strength, starting with the weakest and ending with the strongest.

Unit 7 Review

Topics to Study Properties of Chemical Bonds/Intramolecular Forces (Covalent, Ionic, Metalic) How do they form?; Conduct heat/electricity?; brittle or not?; relative bp/mp?; etc. Molecule vs. Formula Unit Intermolecular Forces (Ion-Dipole, Hydrogen “Bonding”, Dipole-Dipole, Dispersion) When do they form?; Relative strength; Identify the forces that exist between given molecules; Rank molecules based on bp

Metallic Properties Delocalized sea of electrons explains several properties of metals: Good conductors of heat Good conductors of electricity Ductile Malleable Strong High melting and boiling points

Ionic Properties Formula unit Very high melting points Brittle crystalline structures Soluble in water Good conductors of electricity IF melted or dissolved

Covalent Properties Molecule Low melting and boiling points Many are liquids and gases at room temperature Soluble in water IF they are polar (like dissolves like) Do not conduct electricity

Drawing/Identifying Lewis Structures Calculate ΔEN (know the ranges for ionic/polar/nonpolar) Dipole arrows (partial positive and partial negative) Polar or Nonpolar? Geometric Shapes Bond Strength Lattice Energy (Ionic) Charges, then size Covalent Single/Double/Triple Then, Size “Like Dissolves Like”